1. Field of the Invention
The present invention relates to an improved configuration for audio tube speakers, especially those utilized in automotive vehicles.
2. Description of the Prior Art
Audio bass speakers are often constructed with a tubular cylindrical housing that is closed at one end and which has an audio speaker unit mounted at the opposite end. Such bass speakers are often referred to as "woofers" and are of a relatively large size. Commercially available tubular bass speakers designed for use in automotive vehicles typically have an outer tube diameter of six inches, eight inches, ten inches or twelve inches. The speaker tubes may be of any selected length, and are available in a wide variety of lengths. One popular length is about twenty inches. The relatively large size of such tube speakers or "woofers" provides clear and resonant audio propagation for achieving high quality reproduction of low frequency sound.
In recent years high quality sound reproduction systems have gained increased popularity for use in vehicles, such as hatchback and sedan automobiles, vans, station wagons and pick up trucks. The high quality of low frequency sound reproduction achieved with tube speakers has contributed significantly to the popularity of tube speakers among automotive vehicle owners, particularly among younger owners.
When tube speakers are employed in automotive vehicles, they are often merely laid on the floor of a van or on a flat panel in the rear of an automotive vehicle, such as the panel behind the back seat and beneath the rear window of an automobile. Due to their cylindrical shape, tube speakers lying on their sides on flat surfaces in an automotive vehicle will tend to roll about unless restrained. The speakers will roll due to inertia as the vehicle makes turns around corners or brakes to a stop.
The rolling movement of conventional tube speaker systems can damage the sound reproduction units, and in any event is annoying to the occupants of a vehicle. According to conventional practice tube speakers are restrained from rolling by means of straps that are secured about the speaker and fastened to the surfaces upon which the speakers are placed, or by wedging the speakers behind or beneath seats in the vehicle.
One alternative approach to stabilization of a tube speaker in a vehicle is disclosed in U.S. Pat. No. 4,756,382. According to this arrangement, an otherwise cylindrical tube speaker is provided with a laterally directed audio duct that projects outwardly in a plane generally perpendicular to the axis of the tube speaker. The system thus is of a generally T-shaped configuration and is designed to reduce the tendency of the speaker to roll during changes in the velocity of a vehicle without the necessity for external mounting straps or other stabilizing devices. However, by providing the speaker with a duct aligned generally normal to the axis of the speaker, the resonant propagation of sound from the tube speaker that otherwise acts longitudinally along the length of the speaker enclosure is disrupted. Furthermore, the T-shaped configuration of the speaker enclosure increases the width of the space occupied by the speaker on a deck or floor of a vehicle.